Copolymerizable sulfur-containing adhesion promoters and compositions thereof

ABSTRACT

Disclosed are sulfur-containing polymers containing copolymerizable adhesion promoters and compositions including sealant compositions useful in aerospace applications comprising sulfur-containing polymers containing copolymerizable adhesion promoters. In particular, polythioethers and polysulfides incorporating copolymerizable adhesion promoters are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 13/529,183 filed Jun. 21, 2012.

FIELD

The present disclosure relates to polymers in which adhesion promotersare copolymerized to a sulfur-containing polymer backbone and tocompositions comprising the copolymerizable adhesion promoters thatexhibit improved surface adhesion. Sulfur-containing polymersincorporating copolymerizable adhesion promoters and compositionsthereof are disclosed.

BACKGROUND

Sealants useful in aerospace and other applications must satisfydemanding mechanical, chemical, and environmental requirements. Thesealants can be applied to a variety of surfaces including metalsurfaces, primer coatings, intermediate coatings, finished coatings, andaged coatings. Adhesion promoters are typically added to sealantformulations to enhance adhesion of the various components to each otherand to the surfaces to which the sealant is applied. Ways to provideimproved adhesion while maintaining other advantageous properties of asealant are continuously desired.

Sulfur-containing polymers such as polythioethers and polysulfides areuseful in aerospace applications. Examples of polythioethers andpolysulfides are disclosed, for example, in U.S. Publication Nos.2005/0010003, 2006/0270796, 2007/0287810, 2009/0326167, and 2010/036063.

SUMMARY

Copolymerizing adhesion promoters directly to a sulfur-containingpolymer backbone ensures that the adhesion promoters are stronglycoupled to the polymer network, which forms the structure of a curedsealant. Sulfur-containing polymers comprising copolymerizable adhesionpromoters and compositions comprising such polymers are also disclosed.

In a first aspect, sulfur-containing compounds are provided having thestructure of Formula (1):

B(—V′—S—R¹—S-A′)_(z1)(—V′—S—R¹—SH)_(z2)  (1)

wherein

each R¹ is independently selected from C₂₋₆ alkanediyl, C₆₋₈cycloalkanediyl, C₆₋₁₀ alkanecycloalkanediyl, C₅₋₈heterocycloalkanediyl, and —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—;

-   -   wherein:        -   each R³ is independently selected from hydrogen and methyl;        -   each X is independently selected from —O—, —S—, and —NR—    -   wherein R is selected from hydrogen and methyl;        -   s is an integer from 2 to 6;        -   q is an integer from 1 to 5; and        -   r is an integer from 2 to 10;

each A′ independently represents a moiety formed by the reaction of acompound A with a thiol group, wherein compound A is a compound having aterminal group that is reactive with a thiol group and a terminal groupthat promotes adhesion;

B represents a core of a z-valent, alkenyl-terminated polyfunctionalcompound B(—V)_(z),

-   -   wherein:        -   z is the sum of z1 and z2, and z is an integer from 3 to 6;        -   z1 is an integer from 1 to 4;        -   z2 is an integer from 2 to 5; and        -   each —V is a moiety comprising a terminal group that is            reactive with a thiol group; and

each —V′— represents a moiety formed by the reaction of —V with a thiolgroup.

In a second aspect, sulfur-containing compounds are provided comprisingthe reaction product of reactants comprising: (a) a polyfunctionalcompound having terminal groups that are reactive with thiol groups; (b)a dithiol; and (c) a compound having a terminal group that is reactivewith a thiol group and a terminal group that promotes adhesion.

In a third aspect, compositions are provided comprising: (a) at leastone sulfur-containing compound provided by the present disclosure; (b)at least one thiol-terminated sulfur-containing polymer; and (c) atleast one curing agent.

In a fourth aspect, sealants comprising at least one sulfur-containingcompound provided by the present disclosure are provided.

In a fifth aspect, apertures sealed with a sealant comprising at leastone sulfur-containing compound provided by the present disclosure areprovided.

In a sixth aspect, methods of sealing an aperture are providedcomprising: (a) applying a sealant comprising at least onesulfur-containing compound provided by the present disclosure to atleast one surface defining an aperture; (b) assembling the surfacesdefining the aperture; and (c) curing the sealant to provide the curedaperture.

DETAILED DESCRIPTION Definitions

For purposes of the following description, it is to be understood thatembodiments provided by the present disclosure may assume variousalternative variations and step sequences, except where expresslyspecified to the contrary. Moreover, other than in the examples, orwhere otherwise indicated, all numbers expressing, for example,quantities of ingredients used in the specification and claims are to beunderstood as being modified in all instances by the term “about.”Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired properties to beobtained. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the embodiments provided by the present disclosureare approximations, the numerical values set forth in the specificexamples are reported as precisely as possible. Any numerical value,however, inherently contains certain errors necessarily resulting fromthe standard variation found in their respective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges encompassed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of about 1 and the recited maximumvalue of about 10, that is, having a minimum value equal to or greaterthan about 1 and a maximum value of equal to or less than about 10.Also, in this application, the use of “or” means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances.

A dash (“-”) that is not between two letters or symbols is used toindicate a point of bonding for a substituent or between two atoms. Forexample, —CONH₂ is bonded to another chemical moiety through the carbonatom.

“Alkanediyl” refers to a diradical of a saturated, branched orstraight-chain, acyclic hydrocarbon group, having, for example, from 1to 18 carbon atoms (C₁₋₁₈), from 1-14 carbon atoms (C₁₋₁₄), from 1-6carbon atoms (C₁₋₆), from 1 to 4 carbon atoms (C₁₋₄), or from 1 to 3hydrocarbon atoms (C₁₋₃). It can be appreciated that a branchedalkanediyl has a minimum of three carbon atoms. In certain embodiments,the alkanediyl is C₂₋₁₄ alkanediyl, C₂₋₁₀ alkanediyl, C₂₋₈ alkanediyl,C₂₋₆ alkanediyl, C₂₋₄ alkanediyl, and in certain embodiments, C₂₋₃alkanediyl. Examples of alkanediyl groups include methane-diyl (—CH₂—),ethane-1,2-diyl (—CH₂CH₂—), propane-1,3-diyl and iso-propane-1,2-diyl(e.g., —CH₂CH₂CH₂— and —CH(CH₃)CH₂—), butane-1,4-diyl (—CH₂CH₂CH₂CH₂—),pentane-1,5-diyl (—CH₂CH₂CH₂CH₂CH₂—), hexane-1,6-diyl(—CH₂CH₂CH₂CH₂CH₂CH₂—), heptane-1,7-diyl, octane-1,8-diyl,nonane-1,9-diyl, decane-1,10-diyl, dodecane-1,12-diyl, and the like.

“Alkanecycloalkane” refers to a saturated hydrocarbon group having oneor more cycloalkyl and/or cycloalkanediyl groups and one or more alkyland/or alkanediyl groups, where cycloalkyl, cycloalkanediyl, alkyl, andalkanediyl are defined herein. In certain embodiments, each cycloalkyland/or cycloalkanediyl group(s) is C₃₋₆, C₅₋₆, and in certainembodiments, cyclohexyl or cyclohexanediyl. In certain embodiments, eachalkyl and/or alkanediyl group(s) is C₁₋₆, C₁₋₄, C₁₋₃, and in certainembodiments, methyl, methanediyl, ethyl, or ethane-1,2-diyl. In certainembodiments, the alkanecycloalkane group is C₄₋₁₈ alkanecycloalkane,C₄₋₁₆ alkanecycloalkane, C₄₋₁₂ alkanecycloalkane, C₄₋₈alkanecycloalkane, C₆₋₁₂ alkanecycloalkane, C₆₋₁₀ alkanecycloalkane, andin certain embodiments, C₆₋₉ alkanecycloalkane. Examples ofalkanecycloalkane groups include 1,1,3,3-tetramethylcyclohexane andcyclohexylmethane.

“Alkanecycloalkanediyl” refers to a diradical of an alkanecycloalkanegroup. In certain embodiments, the alkanecycloalkanediyl group is C₄₋₁₈alkanecycloalkanediyl, C₄₋₁₆ alkanecycloalkanediyl, C₄₋₁₂alkanecycloalkanediyl, C₄₋₈ alkanecycloalkanediyl, C₆₋₁₂alkanecycloalkanediyl, C₆₋₁₀ alkanecycloalkanediyl, and in certainembodiments, C₆₋₉ alkanecycloalkanediyl. Examples ofalkanecycloalkanediyl groups include1,1,3,3-tetramethylcyclohexane-1,5-diyl and cyclohexylmethane-4,4′-diyl.

“Alkenyl” group refers to a group (R)₂C═C(R)₂ or —RC═C(R)₂ where thealkenyl group is a terminal group and is bonded to a larger molecule. Insuch embodiments, each R may be selected from, for example, hydrogen andC₁₋₃ alkyl. In certain embodiments, each R is hydrogen and an alkenylgroup has the structure —CH═CH₂.

“Alkoxy” refers to a —OR group where R is alkyl as defined herein.Examples of alkoxy groups include methoxy, ethoxy, n-propoxy,isopropoxy, and n-butoxy. In certain embodiments, the alkoxy group isC₁₋₈ alkoxy, C₁₋₆ alkoxy, C₁₋₄ alkoxy, and in certain embodiments, C₁₋₃alkoxy.

“Alkyl” refers to a monoradical of a saturated, branched orstraight-chain, acyclic hydrocarbon group having, for example, from 1 to20 carbon atoms, from 1 to 10 carbon atoms, from 1 to 6 carbon atoms,from 1 to 4 carbon atoms, or from 1 to 3 carbon atoms. In certainembodiments, the alkyl group is C₂₋₆ alkyl, C₂₋₄ alkyl, and in certainembodiments, C₂₋₃ alkyl. Examples of alkyl groups include methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-hexyl, n-decyl,tetradecyl, and the like. In certain embodiments, the alkyl group isC₂₋₆ alkyl, C₂₋₄ alkyl, and in certain embodiments, C₂₋₃ alkyl. It canbe appreciated that a branched alkyl group has a minimum of three carbonatoms.

“Cycloalkanediyl” refers to a diradical saturated monocyclic orpolycyclic hydrocarbon group. In certain embodiments, thecycloalkanediyl group is C₃₋₁₂ cycloalkanediyl, C₃₋₈ cycloalkanediyl,C₃₋₆ cycloalkanediyl, and in certain embodiments, C₅₋₆ cycloalkanediyl.Examples of cycloalkanediyl groups include cyclohexane-1,4-diyl,cyclohexane-1,3-diyl, and cyclohexane-1,2-diyl.

“Cycloalkyl” refers to a saturated monocyclic or polycyclic hydrocarbonmonoradical group. In certain embodiments, the cycloalkyl group is C₃₋₁₂cycloalkyl, C₃₋₈ cycloalkyl, C₃₋₆ cycloalkyl, and in certainembodiments, C₅₋₆ cycloalkyl.

“Heteroalkanediyl” refers to an alkanediyl group in which one or more ofthe carbon atoms are replaced with a heteroatom, such as N, O, S, or P.In certain embodiments of heteroalkanediyl, the heteroatom is selectedfrom N and O.

“Heterocycloalkanediyl” refers to a cycloalkanediyl group in which oneor more of the carbon atoms are replaced with a heteroatom, such as N,O, S, or P. In certain embodiments of heterocycloalkanediyl, theheteroatom is selected from N and O.

A “Michael acceptor” refers to an activated alkene, such as an alkenylgroup proximate to an electron-withdrawing group such as a ketone,nitro, halo, nitrile, carbonyl, or nitro group. Michael acceptors arewell known in the art. A “Michael acceptor group” refers to an activatedalkenyl group and an electron-withdrawing group. In certain embodiments,a Michael acceptor group is selected from a vinyl ketone, a vinylsulfone, a quinone, an enamine, a ketimine, an aldimine, an oxazolidine,and an acrylate. Other examples of Michael acceptors are disclosed inMather et al., Prog. Polym. Sci., 2006, 31, 487-531, and includeacrylate esters, acrylonitrile, acrylamides, maleimides, alkylmethacrylates, cyanoacrylates. Other Michael acceptors include vinylketones, α,β-unsaturated aldehydes, vinyl phosphonates, acrylonitrile,vinyl pyridines, certain azo compounds, β-keto acetylenes and acetyleneesters. In certain embodiments, a Michael acceptor group is derived froma vinyl ketone and has the structure of the formula —S(O)₂—C(R)₂═CH₂,where each R is independently selected from hydrogen, fluorine, and C₁₋₃alkyl. In certain embodiments, each R is hydrogen. In certainembodiments, a Michael acceptor or Michael acceptor group does notencompass acrylates. A “Michael acceptor compound” refers to a compoundcomprising at least one Michael acceptor. In certain embodiments, aMichael acceptor compound is divinyl sulfone, and a Michael acceptorgroup is vinylsulfonyl, e.g., —S(O)₂—CH₂═CH₂.

As used herein, “polymer” refers to oligomers, homopolymers, andcopolymers. Unless stated otherwise, molecular weights are numberaverage molecular weights for polymeric materials indicated as “Mn” asdetermined, for example, by gel permeation chromatography using apolystyrene standard in an art-recognized manner.

“Substituted” refers to a group in which one or more hydrogen atoms areeach independently replaced with the same or different substituent(s).In certain embodiments, the substituent is selected from halogen,—S(O)₂OH, —S(O)₂, —SH, —SR where R is C₁₋₆ alkyl, —COOH, —NO₂, —NR₂where each R is independently selected from hydrogen and C₁₋₃ alkyl,—CN, ═O, C₁₋₆ alkyl, —CF₃, —OH, phenyl, C₂₋₆ heteroalkyl, C₅₋₆heteroaryl, C₁₋₆ alkoxy, and —COR where R is C₁₋₆ alkyl. In certainembodiments, the substituent is chosen from —OH, —NH₂, and C₁₋₃ alkyl.

Reference is now made to certain embodiments of sulfur-containingcompounds, adhesion promoters, polymers, compositions, and methods. Thedisclosed embodiments are not intended to be limiting of the claims. Tothe contrary, the claims are intended to cover all alternatives,modifications, and equivalents.

Sulfur-Containing Adhesion Promoters

Copolymerizing adhesion promoters directly to a sulfur-containingpolymer backbone can improve the adhesion of a composition such as asealant composition. It will be appreciated that the general concept canbe applied to any adhesion promoter and to any polymer.

In certain embodiments, adhesion promoters provided by the presentdisclosure are copolymerized to the backbone of a sulfur-containingpolymer such as a thiol-terminated sulfur-containing polymer, including,for example, thiol-terminated polythioethers and thiol-terminatedpolysulfides.

In certain embodiments, an adhesion promoter is copolymerized to athiol-terminated polythioether polymer. Examples of thiol-functionalpolythioethers are disclosed, for example, in U.S. Pat. No. 6,172,179.In certain embodiments, a thiol-functional polythioether comprisesPermapol® P3.1E, available from PRC-DeSoto International Inc., Sylmar,Calif.

In certain embodiments, an adhesion promoter is copolymerized to apolysulfide polymer. In certain embodiments, a polysulfide polymer canbe any of the polymers disclosed, for example, in U.S. Pat. No.4,623,711.

In certain embodiments, an adhesion promoter useful for copolymerizingto a polymer backbone comprises a sulfur-containing compound having thestructure of Formula (1):

B(—V′—S—R¹—S-A′)_(z1)(—V′—S—R—SH)_(z2)  (1)

wherein

-   -   each R¹ is independently selected from C₂₋₆ alkanediyl, C₆₋₈        cycloalkanediyl, C₆₋₁₀ alkanecycloalkanediyl, C₅₋₈        heterocycloalkanediyl, and —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—;        -   wherein:            -   each R³ is independently selected from hydrogen and                methyl;            -   each X is independently selected from —O—, —S—, and —NR—        -   wherein R is selected from hydrogen and methyl;            -   s is an integer from 2 to 6;            -   q is an integer from 1 to 5; and            -   r is an integer from 2 to 10;    -   each A′ independently represents a moiety formed by the reaction        of a compound A with a thiol group, wherein compound A is a        compound having a terminal group that is reactive with a thiol        group and a terminal group that promotes adhesion;    -   B represents a core of a z-valent, alkenyl-terminated        polyfunctional compound B(—V)_(z),        -   wherein:            -   z is the sum of z1 and z2, and z is an integer from 3 to                6;            -   z1 is an integer from 1 to 4;            -   z2 is an integer from 2 to 5; and            -   each −V is a moiety comprising a terminal group that is                reactive with a thiol group; and    -   each —V′— represents a moiety formed by the reaction of —V with        a thiol group.

Compounds of Formula (1) comprise at least one terminal adhesionpromoter moiety and at least two terminal thiol groups. The at least oneadhesion promoter moiety provides adhesion to a surface and/or otherconstituent of a formulation of which it is a part, and the terminalthiol-groups react with a curing agent to form a polymer network. Thus,in compounds of Formula (1), z2 is at least 2, and in certainembodiments, z2 is 2, 3, 4, and in certain embodiments z2 is 5. Incertain embodiments of compounds of Formula (1), z1 is 1, 2, 3, and incertain embodiments, z1 is 4. In certain embodiments, a compound ofFormula (1) is trivalent, such that z is 3, in certain embodiments, acompound of Formula (1) is tetravalent such that z is 4, and in certainembodiments, z is 5, and in certain embodiments, z is 6.

In certain embodiments, R¹ is selected from C₂₋₆ alkanediyl and—[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—.

In certain embodiments, R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, and incertain embodiments X is —O— and in certain embodiments, X is —S—.

In certain embodiments where R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, pis 2, r is 2, q is 1, and X is —S—; in certain embodiments, p is 2, q is2, r is 2, and X is —O—; and in certain embodiments, p is 2, r is 2, qis 1, and X is —O—.

In certain embodiments where R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—,each R³ is hydrogen, and in certain embodiments, at least one R³ ismethyl.

In certain embodiments of a compound of Formula (1), each R¹ is thesame, and in certain embodiments, at least one R¹ is different.

In certain embodiments of a compound of Formula (1), the terminal groupthat is reactive with a thiol group in compound A is selected from analkenyl group, an isocyanate group, an epoxy group, and a Michaelacceptor group. In certain embodiments of a compound of Formula (1), theterminal group that is reactive with a thiol group in compound A is analkenyl group, an isocyanate group, an epoxy group, and in certainembodiments, a Michael acceptor group.

In certain embodiments of a compound of Formula (1), a terminal groupthat promotes adhesion is selected from a silane, a phosphonate, anamine, a carboxylic acid, and a phosphonic acid. In certain embodimentsof a compound of Formula (1), a terminal group that promotes adhesion isa silane group, a phosphonate group, an amine group, a carboxylic acidgroup, and in certain embodiments, a phosphonic acid group.

—V is a moiety comprising a terminal group that is reactive with a thiolgroup. For example, in certain embodiments, —V is —R¹⁰—CH═CH₂, whereinR¹⁰ is selected from C₁₋₆ alkanediyl, substituted C₁₋₆ alkanediyl, C₁₋₆heteroalkanediyl, and substituted C₁₋₆ heteroalkanediyl. However, thestructure of —V is not limited. In certain embodiments, each —V may bethe same, and in certain embodiments, at least one —V may be different.

Each A′ independently represents a moiety formed by the reaction of acompound A with a thiol group, wherein compound A is a compound having aterminal group that is reactive with a thiol group and a terminal groupthat promotes adhesion. As indicated above, groups that are reactivewith thiol groups include alkenyl groups, isocyanate groups, epoxygroups, and Michael acceptor groups. Groups that promote adhesion arewell-known in the art. Examples of groups that promote adhesion includesilane groups, phosphonate groups, amine groups, including primary andsecondary amines, carboxylic acid groups, and phosphonic acid groups.

In compounds of Formula (1), each A′ may be the same or, in certainembodiments, at least one A′ may be different. For example, in certainembodiments, each A′ may comprise the same adhesion promoting group, andin certain embodiments, at least one of the adhesion promoting groupsmay be different.

In certain embodiments, an adhesion promoting group may be a silanegroup, which may have the structure —Si(R⁴)_(y1)(OR⁵)_(y2) wherein y1 isselected from 0, 1, and 2; y2 is selected from 1, 2, and 3; and the sumof y1 and y2 is 3; each R⁴ is independently selected from C₁₋₄ alkyl;and each R⁵ is independently selected from C₁₋₄ alkyl.

In certain embodiments, an adhesion promoting group may be a phosphonategroup, which may have the structure —P(═O)(OR⁶)₂ wherein each R⁶ isindependently selected from C₁₋₄ alkyl. In certain embodiments, anadhesion promoting group may be a phosphonic acid group, which has thestructure —P(═O)(OR⁶)₂ wherein each R⁶ is hydrogen.

In certain embodiments, an adhesion promoting group may be a primaryamine, and in certain embodiments, a secondary amine.

In certain embodiments, an adhesion promoting group may be a carboxylicacid group.

In certain embodiments of A in which a terminal group that is reactivewith a thiol group is an alkenyl group, A is selected from

(a) a compound of Formula (2):

CH₂═CH₂—R⁴—Si(R⁵)_(y1)(OR⁶)_(y2)  (2)

-   -   wherein        -   y1 is selected from 0, 1, and 2; y2 is selected from 1, 2,            and 3; wherein the sum of y1 and y2 is 3;        -   R⁴ is selected from a covalent bond and C₁₋₆ alkanediyl;        -   each R⁵ is independently selected from C₁₋₄ alkyl; and        -   each R⁶ is independently selected from C₁₋₄ alkyl;

(b) a compound of Formula (3):

CH₂═CH₂—R⁷—P(═O)(OR⁸)₂  (3)

-   -   wherein        -   R⁷ is selected from a covalent bond and C₁₋₆ alkanediyl; and        -   each R⁸ is independently selected from hydrogen and C₁₋₄            alkyl;

(c) a compound of Formula (4):

CH₂═CH₂—R⁹—NH₂  (4)

-   -   wherein R⁹ is selected from C₁₋₁₀ alkanediyl, substituted C₁₋₁₀        alkanediyl, C₁₋₁₀ heteroalkanediyl, and substituted C₁₋₁₀        heteroalkanediyl; and

(d) a compound of Formula (5):

CH₂═CH₂—R¹⁰—COOH  (5)

-   -   wherein R¹⁰ is C₁₋₆ alkanediyl.

In certain embodiments, a group that is reactive with a thiol group is aMichael acceptor group. In certain embodiments, a Michael acceptor groupcomprises a moiety in which an electron withdrawing group such as aketone or a sulfone is proximate to a terminal alkenyl group. Examplesof Michael acceptor groups include vinyl ketones, vinyl sulfones,quinones, enamines, aldimines, ketimines, and acrylates. Other examplesof electron withdrawing groups include a hindered secondary amine group,a tertiary amine group, an aziridinyl group, a urea group, a carbamategroup, a carbodiimide group, and a halogen group. Accordingly, in suchembodiments, compound A comprises a Michael acceptor group and a groupthat promotes adhesion.

In certain embodiments of a compound of Formula (1), each -A′ is thesame and is selected from Formula (2a), Formula (3a), Formula (4a), andFormula (5a):

—CH₂—CH₂—R⁴—Si(R⁵)_(y1)(OR⁶)_(y2)  (2a)

—CH₂—CH₂—R⁷—P(═O)(OR⁸)₂  (3a)

—CH₂—CH₂—R⁹—NH₂  (4a)

—CH₂—CH₂—R¹⁰—COOH  (5a)

where R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are as defined for Formulae(2)-(5).

In certain embodiments of a compound of Formula (1), each —A′ is thesame and is a moiety of Formula (2a), a moiety of Formula (3a), a moietyof Formula (4a), and in certain embodiments, a moiety of Formula (5a).

In certain embodiments in which compound A comprises a Michael acceptorgroup, compound A comprises the reaction products of (a) a compound ofthe formula HS—R¹⁰—S-D, wherein R¹⁰ is selected from C₁₋₁₀ alkanediyl,substituted C₁₋₁₀ alkanediyl, C₁₋₁₀ heteroalkanediyl, and substitutedC₁₋₁₀ heteroalkanediyl; and D comprises a terminal group that promotesadhesion; and (b) a compound having terminal Michael acceptor group anda terminal group that is reactive with a thiol group. In certainembodiments, a terminal Michael acceptor group is a vinyl sulfone and aterminal group that is reactive with a thiol group is selected from analkenyl group and an epoxy group. In certain embodiments, compound A isdivinyl sulfone.

In certain embodiments, a compound having a terminal Michael acceptorgroup and a terminal group that promotes adhesion has the formulaCH₂═S(O)₂—CH₂—S—R¹⁰—S-D. Such compounds may be reacted with a polythiol,such as a trithiol, a tetrathiol, a pentathiol, a hexathiol, or acombination of any of the foregoing. Polythiols can have the structureB(—V)_(z) wherein each —V is a moiety having a terminal thiol group andz is an integer from 3 to 6. Examples of suitable polythiols aredisclosed in U.S. Publication No. 2011/0319559.

In certain embodiments of a compound of Formula (1), each -A′ is thesame and is selected from Formula (2b), Formula (3b), Formula (4b), andFormula (5b):

—(CH₂)₂—S(O)₂—(CH₂)₂—S—R⁴—Si(R⁵)_(y1)(OR⁶)_(y2)  (2b)

—(CH₂)₂—S(O)₂—(CH₂)₂—S—R⁷—P(═O)(OR⁸)₂  (3b)

—(CH₂)₂—S(O)₂—(CH₂)₂—S—R⁹—NH₂  (4b)

—(CH₂)₂—S(O)₂—(CH₂)₂—S—R¹⁰—COOH  (5b)

where R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are as defined for Formulae(2)-(5). In certain embodiments of a compound of Formula (1), each -A′is the same and is a moiety of Formula (2b), a moiety of Formula (3b), amoiety of Formula (4b), and in certain embodiments, a moiety of Formula(5b).

B represents a core of a z-valent, polyfunctional compound B(—V)_(z),where z is an integer from 3 to 6. In certain embodiments, z is 3, z is4, z is 5, and in certain embodiments z is 6. In certain embodiments, apolyfunctional compound is trifunctional. In certain embodiments, apolyfunctional compounds is triallyl cyanurate (TAC) where B has thestructure:

and each —V has the structure —O—CH₂—CH═CH₂.

In certain embodiments, polyfunctional compound B(—V)_(z) has amolecular weight less than 800 Daltons, less than 600 Daltons, less than400 Daltons and in certain embodiments, less than 200 Daltons.Polyfunctional compounds B(—V)_(z) in which z is at least 3 may be anyof the polyfunctionalizing agents useful in polymer chemistry.Polyfunctionalizing agents having mixed functionality, i.e., agents thatinclude moieties (typically separate moieties), that react with boththiol and vinyl groups, may also be employed. Other usefulpolyfunctionalizing agents include trimethylolpropane trivinyl ether,and the polythiols described in U.S. Pat. No. 4,366,307, U.S. Pat. No.4,609,762, and U.S. Pat. No. 5,225,472, each of which is incorporated byreference in its entirety. Combinations of polyfunctionalizing agentshaving the same terminal groups such as thiol groups or allyl groups mayalso be used.

Each —V is a moiety comprising a terminal group that is reactive with athiol group such as, for example, an alkenyl group, an epoxy group, or aMichael acceptor group. In certain embodiments, each —V is the same, andin certain embodiments, at least one —V is different. In certainembodiments, —V is selected from C₃₋₈ alkene-1-yl and C₃₋₈heteroalkene-1-yl, where the one or more hetero groups is selected from—O— and —S—.

Each —V′— represents a moiety formed by the reaction of a moiety —V witha thiol group. In certain embodiments, —V comprises a terminal alkenylgroup selected from C₃₋₈ alkene-1-yl and C₃₋₈ heteroalkene-1-yl, and V′is selected from C₃₋₈ alkanediyl and C₃₋₈ heteroalkanediyl.

Reaction Product

In certain embodiments, a sulfur-containing adhesion promoter comprisesthe reaction products of reactants comprising: (a) a polyfunctionalsulfur-containing compound having terminal groups that are reactive withthiol groups; (b) a dithiol; and (c) a compound having a terminal groupthat is reactive with a thiol group and a terminal second group thatpromotes adhesion. In certain embodiments of the reaction, the reactionproducts comprise one or more compounds of Formula (1).

In certain embodiments, a polyfunctional compound having terminal groupsreactive with thiol groups has the structure B(—V)_(z) where z is aninteger from 3 to 6, and B and —V are as defined herein.

In certain embodiments of B(—V)_(z), each —V comprises a terminalalkenyl group.

In certain embodiments, a dithiol has the structure of Formula (6):

HS—R¹—SH  (6)

wherein:

-   -   R¹ is selected from C₂₋₆ alkanediyl, C₆₋₈ cycloalkanediyl, C₆₋₁₀        alkanecycloalkanediyl, C₅₋₈ heterocycloalkanediyl, and        —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—;    -   wherein:        -   each R³ is independently selected from hydrogen and methyl;        -   each X is independently selected from —O—, —S—, and —NR—            wherein R is selected from hydrogen and methyl;        -   s is an integer from 2 to 6;        -   q is an integer from 1 to 5; and        -   r is an integer from 2 to 10.

In certain embodiments, R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—.

In certain embodiments of a compound of Formula (6), X is selected from—O— and —S—, and thus —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)— in Formula (6)is —[(—CH₂—)_(p)O—]_(q)—(CH₂)_(r)— or —[(—CH₂—)_(p)—S—]_(q)—(CH₂)_(r)—.In certain embodiments, p and r are equal, such as where p and r areboth two.

In certain embodiments, R¹ is selected from C₂₋₆ alkanediyl and—[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—.

In certain embodiments, R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, and incertain embodiments X is —O—, and in certain embodiments, X is —S—.

In certain embodiments, where R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, pis 2, r is 2, q is 1, and X is —S—; in certain embodiments, p is 2, q is2, r is 2, and X is —O—; and in certain embodiments, p is 2, r is 2, qis 1, and X is —O—.

In certain embodiments, where R¹ is —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—,each R³ is hydrogen, and in certain embodiments, at least one R³ ismethyl.

In certain embodiments of a compound of Formula (1), each R¹ is thesame, and in certain embodiments, at least one R¹ is different.

Examples of suitable dithiols include, for example, 1,2-ethanedithiol,1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol,1,4-butanedithiol, 2,3-butanedithiol, 1,3-pentanedithiol,1,5-pentanedithiol, 1,6-hexanedithiol, 1,3-dimercapto-3-methylbutane,dipentenedimercaptan, ethylcyclohexyldithiol (ECHDT),dimercaptodiethylsulfide, methyl-substituted dimercaptodiethylsulfide,dimethyl-substituted dimercaptodiethylsulfide, dimercaptodioxaoctane,1,5-dimercapto-3-oxapentane, and a combination of any of the foregoing.A polythiol may have one or more pendant groups selected from a lower(e.g., C₁₋₆) alkyl group, a lower alkoxy group, and a hydroxyl group.Suitable alkyl pendant groups include, for example, C₁₋₆ linear alkyl,C₃₋₆ branched alkyl, cyclopentyl, and cyclohexyl.

Other examples of suitable dithiols include dimercaptodiethylsulfide(DMDS) (in Formula (6), R¹ is —[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)—, whereinp is 2, r is 2, q is 1, and X is —S—); dimercaptodioxaoctane (DMDO) (inFormula (6), R¹ is —[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)—, wherein p is 2, qis 2, r is 2, and X is —O—); and 1,5-dimercapto-3-oxapentane (in Formula(6), R¹ is —[(—CH₂—)_(p)X—]_(q)—(CH₂)_(r)—, wherein p is 2, r is 2, q is1, and X is —O—). It is also possible to use dithiols that include bothheteroatoms in the carbon backbone and pendant alkyl groups, such asmethyl groups. Such compounds include, for example, methyl-substitutedDMDS, such as HS—CH₂CH(CH₃)—S—CH₂CH₂—SH, HS—CH(CH₃)CH₂—S—CH₂CH₂—SH anddimethyl substituted DMDS, such as HS—CH₂CH(CH₃)—S—CHCH₃CH₂—SH andHS—CH(CH₃)CH₂—S—CH₂CH(CH₃)—SH.

In certain embodiments of a compound having a terminal group that isreactive with a thiol group and a terminal group that promotes adhesion,the terminal group that is reactive with a thiol group is selected froman alkenyl group, an isocyanate group, an epoxy group, and a Michaelacceptor group; and the terminal group that promotes adhesion isselected from a silane, a phosphonate, an amine, a carboxylic acid, anda phosphonic acid.

In certain embodiments, a compound having a first group that is reactivewith a thiol group and a second group that promotes adhesion is a vinylsilane. In certain embodiments, a vinyl silane has the structure ofFormula (2):

CH₂═CH₂—R⁴—Si(R⁵)_(y1)(OR⁶)_(y2)  (2)

wherein

-   -   y1 is selected from 0, 1, and 2; y2 is selected from 1, 2, and        3; wherein the sum of y1 and y2 is 3;    -   R⁴ is selected from a covalent bond and C₁₋₆ alkanediyl;    -   each R⁵ is independently selected from C₁₋₄ alkyl; and    -   each R⁶ is independently selected from C₁₋₄ alkyl.

In certain embodiments, a vinyl silane is selected fromtrimethoxy(vinyl)silane, ethoxydimethoxy(vinyl)silane,diethoxy(methoxy)(vinyl)silane, triethoxy(vinyl)silane, and acombination of any of the foregoing.

In certain embodiments, a compound having a terminal group that isreactive with a thiol group and a terminal group that promotes adhesionis a vinyl phosphonate. In certain embodiments, a vinyl phosphonate hasthe structure of Formula (3):

CH₂═CH₂—R⁷—P(═O)(OR⁸)₂  (3)

wherein

-   -   R⁷ is selected from a covalent bond and C₁₋₆ alkanediyl; and    -   each R⁸ is independently selected from hydrogen and C₁₋₄ alkyl.

In certain embodiments, a vinyl phosphonate is selected fromvinylphosphonic acid, dimethyl vinylphosphonate, ethyl methylvinylphosphonate, diethyl vinylphosphonate, and a combination of any ofthe foregoing.

In certain embodiments, that promotes adhesion compound having aterminal group that is reactive with a thiol group and a terminal groupthat promotes adhesion is a vinyl amine. In certain embodiments, a vinylamine has the structure of Formula (4):

CH₂═CH₂—R⁹—NH₂  (4)

where R⁹ is selected from C₁₋₁₀ alkanediyl, substituted C₁₋₁₀alkanediyl, C₁₋₁₀ heteroalkanediyl, and substituted C₁₋₁₀heteroalkanediyl.

In certain embodiments, a vinyl amine comprises the reaction products ofreactants comprising a vinyl epoxide and a diamine. In certainembodiments, the vinyl epoxide has the structure of Formula (7):

where R¹¹ is C₁₋₆ alkanediyl. In certain embodiments, a vinyl epoxide isallyl glycidyl ether. In certain embodiments, the diamine has thestructure of Formula (8):

NH₂—R¹²—NH₂  (8)

where R¹² is C₁₋₆ alkanediyl. In certain embodiments, a diamine isselected from N-(aminomethyl)methanediamine,N¹-(2-aminoethyl)ethane-1,2-diamine, and a combination thereof.

In certain embodiments, the compound having a terminal group that isreactive with a thiol group and a terminal group that promotes adhesionis a vinyl carboxylic acid and has the structure of Formula (5):

CH₂═CH₂—R¹⁰—COOH  (5)

where R¹⁰ is C₁₋₆ alkanediyl. In certain embodiments, a vinyl carboxylicacid is selected from but-3-enoic acid, pent-4-enoic acid, andhex-5-enoic acid.

In certain embodiments, the terminal group that is reactive with a thiolgroup is a Michael acceptor group; and the terminal group that promotesadhesion is selected from a silane, a phosphonate, an amine, acarboxylic acid, and a phosphonic acid. In certain embodiments, thecompound may be prepared by reacting (a) a thiol-terminated compound ofthe formula HS—R—S-D, wherein R is selected from C₁₋₁₀ alkanediyl,substituted C₁₋₁₀ alkanediyl, C₁₋₁₀ heteroalkanediyl, and substitutedC₁₋₁₀ heteroalkanediyl; and D comprises a group that promotes adhesion;with (b) a compound comprising a group that is reactive with a thiolgroup and a Michael acceptor group. In certain embodiments, a compoundcomprising a group that is reactive with a thiol group and a Michaelacceptor group is a vinyl sulfone. In certain embodiments, a compoundcomprising a group that is reactive with a thiol group and a Michaelacceptor group is divinyl sulfone.

In certain embodiments of a reaction to form a sulfur-containingcompound, the polyfunctionalizing agent and the dithiol may be reactedto form a thiol-terminated intermediate. As such, the molar ratios ofthe reactants are appropriately selected. For example, one mole of atrifunctional compound such as TAC can be reacted with three moles of adithiol such as DMDO to provide a trifunctional, thiol-terminatedintermediate. A trifunctional, thiol-terminated intermediate maysubsequently be reacted with a compound comprising a group that isreactive with a thiol group and a group that promotes adhesion. Themolar ratio of the intermediate and a compound comprising a group thatis reactive with a thiol group and a group that promotes adhesion may beselected to provide a polyfunctional compound having a desired averageadhesion promoter functionality. For example, to obtain an averageadhesion promoter functionality of about one, about one mole ofpolyfunctional intermediate is reacted with about one mole of a compoundcomprising a terminal group that is reactive with a thiol group and aterminal group that promotes adhesion.

In sulfur-containing compounds comprising adhesion promoting groupsprovided by the present disclosure it is intended that the compoundscomprise at least one terminal group that promotes adhesion and at leasttwo terminal thiol groups capable of reacting with a curing agent andthereby be incorporated into the backbone of the polymer network, e.g.,copolymerized. In certain embodiments, the sulfur-containing compoundcomprises, on average, a single adhesion promoting group per molecule,and in certain embodiments, an average of two adhesion promoting groupsper molecule.

In certain embodiments, a sulfur-containing adhesion promoter comprisesthe reaction products of reactants comprising TAC, DMDO, and a vinylsilane selected from trimethoxy(vinyl)silane,ethoxydimethoxy(vinyl)silane, diethoxy(methoxy)(vinyl)silane, andtriethoxy(vinyl)silane.

In certain embodiments, a sulfur-containing adhesion promoter comprisesthe reaction products of reactants comprising TAC, DMDO, and a vinylphosphonate selected from vinylphosphonic acid, dimethylvinylphosphonate, ethyl methyl vinylphosphonate, and diethylvinylphosphonate.

In certain embodiments, a sulfur-containing adhesion promoter comprisesthe reaction products of reactants comprising TAC, DMDO, and a diamineselected from N-(aminomethyl)methanediamine andN¹-(2-aminoethyl)ethane-1,2-diamine.

Compositions

Sulfur-containing adhesion promoters provided by the present disclosuremay be used in compositions, such as compositions formulated as sealantsuseful in the aerospace industry.

In certain embodiments, compositions such as sealants provided by thepresent disclosure comprise (a) at least one sulfur-containing compoundprovided by the present disclosure; (b) at least one thiol-terminatedsulfur-containing polymer; and (c) at least one curing agent.

In certain embodiments, a thiol-terminated sulfur-containing polymer isselected from a thiol-terminated polythioether, a thiol-terminatedpolysulfide, and a combination thereof.

In certain embodiments, a thiol-terminated sulfur-containing polymercomprises a thiol-terminated polythioether. A thiol-terminatedpolythioether may comprise a mixture of different polythioethers and thepolythioethers may have the same or different functionality of thiolgroups. In certain embodiments, a thiol-terminated polythioether has anaverage functionality from 2 to 6, from 2 to 4, from 2 to 3, and incertain embodiments, from 2.05 to 2.8. For example, a thiol-terminatedpolythioether may be selected from a difunctional sulfur-containingpolymer, a trifunctional sulfur-containing polymer, and a combinationthereof.

Examples of thiol-functional polythioethers are disclosed, for examplein U.S. Pat. No. 6,172,179. In certain embodiments, a thiol-functionalpolythioether comprises Permapol® P3.1E available from PRC-DeSotoInternational Inc., Sylmar, Calif.

In certain embodiments, a thiol-terminated polythioether comprises (a) abackbone comprising a structure having the Formula (12):

—R¹—[—S—(CH₂)₂—O—[—R²—O—]_(m)—(CH₂)₂—S—R¹]_(n)—  (12)

where (i) each R¹ is independently selected from a C₂₋₁₀ n-alkanediylgroup, a C₃₋₆ branched alkanediyl group, a C₆₋₈ cycloalkanediyl e group,a C₆₋₁₀ alkanecycloalkanediyl group, a heterocyclic group, a—[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)— group, and a—[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)— group in which at least one —CH₂— unitis substituted with a methyl group; (ii) each R² is independentlyselected from a C₂₋₁₀ n-alkanediyl group, a C₃₋₆ branched alkanediylgroup, a C₆₋₈ cycloalkanediyl group, a C₆₋₁₄ alkanecycloalkanediylgroup, a heterocyclic group, and a —[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)—group; (iii) each X is independently selected from O, S, and a —NR⁶—group, in which R⁶ is selected from hydrogen and a methyl group; (iv) mranges from 0 to 50; (v) n is an integer from 1 to 60; (vi) p is aninteger from 2 to 6; (vii) q is an integer from 1 to 5; and (viii) r isan integer from 2 to 10.

In certain embodiments, a thiol-terminated polythioether is selectedfrom a thiol-terminated polythioether of Formula (13), athiol-terminated polythioether of Formula (13a), and a combinationthereof:

HS—R¹—[—S—(CH₂)_(p)—O—(R²—O)_(m)—(CH₂)₂—S—R¹—]_(n)—SH  (13)

{HS—R¹—[—S—(CH₂)_(p)—O—(R²—O)_(m)—(CH₂)₂—S—R¹—]_(n)—S—V′—}_(z)B  (13a)

-   -   where:        -   each R¹ independently is selected from C₂₋₆ alkanediyl, C₆₋₈            cycloalkanediyl, C₆₋₁₀ alkanecycloalkanediyl, C₅₋₈            heterocycloalkanediyl, and            —[(—CHR³—)_(s)—X—]_(q)—(—CHR³—)_(r)—,    -   where:        -   s is an integer from 2 to 6;        -   q is an integer from 1 to 5;        -   r is an integer from 2 to 10;        -   each R³ is independently selected from hydrogen and methyl;            and        -   each X is independently selected from O, S, and —NHR—, where            R is selected from hydrogen and methyl;    -   each R² is independently selected from C₁₋₁₀ alkanediyl, C₆₋₈        cycloalkanediyl, C₆₋₁₄ alkanecycloalkanediyl, and        —[(—CHR³—)_(s)—X—]_(q)—(—CHR³—)_(r)—, wherein s, q, r, R³, and X        are as defined above;    -   m is an integer from 0 to 50;    -   n is an integer from 1 to 60;    -   p is an integer from 2 to 6;    -   B represents a core of a z-valent, a polyfunctional compound        B(—V)_(z) wherein:        -   z is an integer from 3 to 6; and        -   each —V is a moiety comprising a terminal group that is            reactive with a thiol group; and    -   each —V′— represents a moiety formed by the reaction of each —V        with a thiol group.

In certain embodiments, R¹ in Formula (13) and in Formula (13a) is—[(—CH₂—)_(p)—X—]_(q)—(CH₂)_(r)—, where p is 2, X is —O—, q is 2, r is2, R² is ethanediyl, m is 2, and n is 9.

In certain embodiments of Formula (13) and Formula (13a), R¹ is selectedfrom C₂₋₆ alkanediyl and —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—.

In certain embodiments of Formula (13) and Formula (13a), R¹ is—[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, and in certain embodiments X is —O—and in certain embodiments, X is —S—.

In certain embodiments of Formula (13) and Formula (13a), where R¹ is—[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, p is 2, r is 2, q is 1, and X is —S—;in certain embodiments, p is 2, q is 2, r is 2, and X is —O—; and incertain embodiments, p is 2, r is 2, q is 1, and X is —O—.

In certain embodiments of Formula (13) and Formula (13a), where R¹ is—[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—, each R³ is hydrogen, and in certainembodiments, at least one R³ is methyl.

In certain embodiments of compounds of Formula (13) and Formula (13a),each R¹ is the same, and in certain embodiments, at least one R¹ isdifferent.

Various methods can be used to prepare such polythioethers. Examples ofsuitable thiol-functional polythioethers, and methods for theirproduction, which are suitable for use in compositions disclosed herein,are described in U.S. Pat. No. 6,172,179 at col. 2, line 29 to col. 4,line 22; col. 6, line 39 to col. 10, line 50; and col. 11, lines 65 tocol. 12, line 22, the cited portions of which are incorporated herein byreference. Such thiol-functional polythioethers may be difunctional,that is, linear polymers having two thiol end groups, or polyfunctional,that is, branched polymers have three or more thiol end groups. Suitablethiol-functional polythioethers are commercially available, for example,as Permapol® P3.1E from PRC-DeSoto International Inc., Sylmar, Calif.

Suitable thiol-functional polythioethers may be produced by reacting adivinyl ether or mixtures of divinyl ethers with an excess of dithiol ora mixtures of dithiols. For example, dithiols suitable for use inpreparing such thiol-functional polythioethers include those havingFormula (6), other dithiols disclosed herein, or combinations of any ofthe dithiols disclosed herein.

Suitable divinyl ethers include, for example, divinyl ethers haveFormula (14): CH₂═CH—O—(—R²—O—)_(m)—CH═CH₂ (14) where R² in Formula (14)is selected from a C₂₋₆ n-alkanediyl group, a C₃₋₆ branched alkanediylgroup, a C₆₋₈ cycloalkanediyl group, a C₆₋₁₀ alkanecycloalkanediylgroup, and —[(—CH₂—)_(p)—O—]_(q)—(—CH₂—)_(r)—, where p is an integerranging from 2 to 6, q is an integer from 1 to 5, and r is an integerfrom 2 to 10. In certain embodiments of a divinyl ether of Formula (14),R² is a C₂₋₆ n-alkanediyl group, a C₃₋₆ branched alkanediyl group, aC₆₋₈ cycloalkanediyl group, a C₆₋₁₀ alkanecycloalkanediyl group, and incertain embodiments, —[(—CH₂—)_(p)—O—]_(q)—(—CH₂—)_(r)—.

Suitable divinyl ethers include, for example, compounds having at leastone oxyalkanediyl group, such as from 1 to 4 oxyalkanediyl groups, i.e.,compounds in which m in Formula (14) is an integer ranging from 1 to 4.In certain embodiments, m in Formula (14) is an integer ranging from 2to 4. It is also possible to employ commercially available divinyl ethermixtures that are characterized by a non-integral average value for thenumber of oxyalkanediyl units per molecule. Thus, m in Formula (14) canalso take on rational number values ranging from 0 to 10.0, such as from1.0 to 10.0, from 1.0 to 4.0, or from 2.0 to 4.0.

Examples of suitable divinyl ethers include, for example, divinyl ether,ethylene glycol divinyl ether (EG-DVE) (R² in Formula (14) is ethanediyland m is 1), butanediol divinyl ether (BD-DVE) (R² in Formula (14) isbutanediyl and m is 1), hexanediol divinyl ether (HD-DVE) (R² in Formula(14) is hexanediyl and m is 1), diethylene glycol divinyl ether(DEG-DVE) (R² in Formula (4) is ethanediyl and m is 2), triethyleneglycol divinyl ether (R² in Formula (14) is ethanediyl and m is 3),tetraethylene glycol divinyl ether (R² in Formula (14) is ethanediyl andm is 4), cyclohexanedimethanol divinyl ether, polytetrahydrofuryldivinyl ether; trivinyl ether monomers, such as trimethylolpropanetrivinyl ether; tetrafunctional ether monomers, such as pentaerythritoltetravinyl ether; and combinations of two or more such polyvinyl ethermonomers. A polyvinyl ether may have one or more pendant groups selectedfrom alkyl groups, hydroxyl groups, alkoxy groups, and amine groups.

In certain embodiments, divinyl ethers in which R² in Formula (14) isC₃₋₆ branched alkanediyl may be prepared by reacting a polyhydroxycompound with acetylene. Examples of divinyl ethers of this type includecompounds in which R² in Formula (14) is an alkyl-substitutedmethanediyl group such as —CH(CH₃)— (for example Pluriol® blends such asPluriol®E-200 divinyl ether (BASF Corp., Parsippany, N.J.), for which R²in Formula (14) is ethanediyl and m is 3.8) or an alkyl-substitutedethanediyl (for example —CH₂CH(CH₃)— such as DPE polymeric blendsincluding DPE-2 and DPE-3 (International Specialty Products, Wayne,N.J.)).

Other useful divinyl ethers include compounds in which R² in Formula(14) is polytetrahydrofuryl (poly-THF) or polyoxyalkanediyl, such asthose having an average of about 3 monomer units.

Two or more types of polyvinyl ether monomers of Formula (14) may beused. Thus, in certain embodiments, two dithiols of Formula (6) and onepolyvinyl ether monomer of Formula (14), one dithiol of Formula (6) andtwo polyvinyl ether monomers of Formula (14), two dithiols of Formula(6) and two divinyl ether monomers of Formula (14), and more than twocompounds of one or both formulas, may be used to produce a variety ofthiol-functional polythioethers.

In certain embodiments, a polyvinyl ether monomer comprises 20 to lessthan 50 mole percent of the reactants used to prepare a thiol-functionalpolythioether, and, in certain embodiments, 30 to less than 50 molepercent.

In certain embodiments provided by the present disclosure, relativeamounts of dithiols and divinyl ethers are selected to yield terminalthiol groups. Thus, a dithiol of Formula (6) or a mixture of at leasttwo different dithiols of Formula (6), are reacted with of a divinylether of Formula (14) or a mixture of at least two different divinylethers of Formula (14) in relative amounts such that the molar ratio ofthiol groups to vinyl groups is greater than 1:1, such as 1.1 to2.0:1.0.

The reaction between compounds of dithiols and divinyl ethers may becatalyzed by a free radical catalyst. Suitable free radical catalystsinclude, for example, azo compounds, for example azobisnitriles such asazo(bis)isobutyronitrile (AIBN); organic peroxides such as benzoylperoxide and t-butyl peroxide; and inorganic peroxides such as hydrogenperoxide. The catalyst may be a free-radical catalyst, an ioniccatalyst, or ultraviolet radiation. In certain embodiments, the catalystdoes not comprise acidic or basic compounds, and does not produce acidicor basic compounds upon decomposition. Examples of free-radicalcatalysts include azo-type catalyst, such as Vazo®-57 (Du Pont),Vazo®-64 (Du Pont), Vazo®-67 (Du Pont), V-70® (Wako SpecialtyChemicals), and V-65B® (Wako Specialty Chemicals). Examples of otherfree-radical catalysts are alkyl peroxides, such as t-butyl peroxide.The reaction may also be effected by irradiation with ultraviolet lighteither with or without a cationic photoinitiating moiety.

Thiol-functional polythioethers provided by the present disclosure maybe prepared by combining at least one compound of Formula (6) and atleast one compound of Formula (14) followed by addition of anappropriate catalyst, and carrying out the reaction at a temperaturefrom 30° C. to 120° C., such as 70° C. to 90° C., for a time from 2 to24 hours, such as 2 to 6 hours.

As disclosed herein, thiol-terminated polythioethers may comprise apolyfunctional polythioether, i.e., may have an average functionality ofgreater than 2.0. Suitable polyfunctional thiol-terminatedpolythioethers include, for example, those having the structure ofFormula (15):

B(-A-SH)_(z)  (15)

wherein: (i) A comprises a structure of Formula (15), (ii) B denotes az-valent residue of a polyfunctionalizing agent; and (iii) z has anaverage value of greater than 2.0, and, in certain embodiments, a valuebetween 2 and 3, a value between 2 and 4, a value between 3 and 6, andin certain embodiments, is an integer from 3 to 6.

Polyfunctionalizing agents suitable for use in preparing suchpolyfunctional thiol-functional polymers include trifunctionalizingagents, that is, compounds where z is 3. Suitable trifunctionalizingagents include, for example, triallyl cyanurate (TAC),1,2,3-propanetrithiol, isocyanurate-containing trithiols, andcombinations thereof, as disclosed in U.S. Publication No. 2010/0010133at paragraphs [0102]-[0105], the cited portion of which is incorporatedherein by reference. Other useful polyfunctionalizing agents includetrimethylolpropane trivinyl ether, and the polythiols described in U.S.Pat. Nos. 4,366,307; 4,609,762; and 5,225,472. Mixtures ofpolyfunctionalizing agents can also be used.

As a result, thiol-functional polythioethers suitable for use inembodiments provided by the present disclosure may have a wide range ofaverage functionality. For example, trifunctionalizing agents may affordaverage functionalities from 2.05 to 3.0, such as from 2.1 to 2.6. Widerranges of average functionality may be achieved by using tetrafunctionalor higher functionality polyfunctionalizing agents. Functionality mayalso be affected by factors such as stoichiometry, as will be understoodby those skilled in the art.

Thiol-functional polythioethers having a functionality greater than 2.0may be prepared in a manner similar to the difunctional thiol-functionalpolythioethers described in U.S. Publication No. 2010/0010133. Incertain embodiments, polythioethers may be prepared by combining (i) oneor more dithiols described herein, with (ii) one or more divinyl ethersdescribed herein, and (iii) one or more polyfunctionalizing agents. Themixture may then be reacted, optionally in the presence of a suitablecatalyst, to afford a thiol-functional polythioether having afunctionality greater than 2.0.

Thus, in certain embodiments, a thiol-terminated polythioether comprisesthe reaction product of reactants comprising:

(a) a dithiol of Formula (6):

HS—R¹—SH  (6)

-   -   wherein:        -   R¹ is selected from C₂₋₆ alkanediyl, C₆₋₈ cycloalkanediyl,            C₆₋₁₀ alkanecycloalkanediyl, C₅₋₈ heterocycloalkanediyl, and            —[—(CHR³)_(s)—X—]_(q)—(CHR³)_(r)—; wherein:            -   each R³ is independently selected from hydrogen and                methyl;            -   each X is independently selected from —O—, —S—, —NH—,                and —NR— wherein R is selected from hydrogen and methyl;            -   s is an integer from 2 to 6;            -   q is an integer from 1 to 5; and            -   r is an integer from 2 to 10; and

(b) a divinyl ether of Formula (14):

CH₂═CH—O—[—R²—O—]_(m)—CH═CH₂  (14)

-   -   wherein:        -   each R² is independently selected from C₁₋₁₀ alkanediyl,            C₆₋₈ cycloalkanediyl, C₆₋₁₄ alkanecycloalkanediyl, and            —[(—CHR³—)_(s)—X—]_(q)—(—CHR³—)_(r)—, wherein s, q, r, R³,            and X are as defined above;        -   m is an integer from 0 to 50;        -   n is an integer from 1 to 60; and        -   p is an integer from 2 to 6.            And, in certain embodiments, the reactants comprise (c) a            polyfunctional compound such as a polyfunctional compound            B(—V)_(z), where B, —V, and z are as defined herein.

Thiol-terminated polythioethers provided by the present disclosurerepresent thiol-terminated polythioethers having a molecular weightdistribution. In certain embodiments, thiol-terminated polythioethersuseful in compositions can exhibit a number average molecular weightranging from 500 Daltons to 20,000 Daltons, in certain embodiments, from2,000 Daltons to 5,000 Daltons, and in certain embodiments, from 3,000Daltons to 4,000 Daltons. In certain embodiments, thiol-terminatedpolythioethers useful in compositions provided by the present disclosureexhibit a polydispersity (M_(w)/M_(n); weight average molecularweight/number average molecular weight) ranging from 1 to 20, and incertain embodiments, from 1 to 5. The molecular weight distribution ofthiol-terminated polythioethers may be characterized by gel permeationchromatography.

In certain embodiments, a thiol-terminated sulfur-containing polymercomprises a thiol-terminated polysulfide.

As used herein, the term “polysulfide” refers to a polymer that containsone or more disulfide linkages, i.e., —[S—S]— linkages, in the polymerbackbone and/or in the terminal or pendant positions on the polymerchain. Often, a polysulfide polymer will have two or more sulfur-sulfurlinkages. Suitable polysulfides are commercially available from AkzoNobel under the name Thioplast®. Thioplast® products are available in awide range of molecular weights ranging, for example, from less than1,100 to over 8,000, with molecular weight being the average molecularweight in grams per mole. In certain embodiments, a polysulfide has anumber average molecular weight of 1,000 to 4,000. The crosslink densityof these products also varies, depending on the amount of crosslinkingagent used. The —SH content, i.e., mercaptan or thiol content, of theseproducts can also vary. The mercaptan content and molecular weight ofthe polysulfide can affect the cure speed of the polymer, with curespeed increasing with molecular weight.

In certain embodiments, in addition to or in lieu of, a polysulfide aspreviously described, comprising thiol-terminated polysulfide comprisesa polymeric mixture comprising: (a) from 90 mole percent to 25 molepercent of mercaptan terminated disulfide polymer of the formulaHS(RSS)_(m)R′SH; and (b) from 10 mole percent to 75 mole percent ofdiethyl formal mercaptan terminated polysulfide polymer of the formulaHS(RSS)_(n)RSH, wherein R is —C₂H₄—O—CH₂—O—C₂H₄—; R′ is a divalentmember selected from alkyl of from 2 to 12 carbon atoms, alkyl thioetherof from 4 to 20 carbon atoms, alkyl ether of from 4 to 20 carbon atomsand one oxygen atom, alkyl ether of from 4 to 20 carbon atoms and from 2to 4 oxygen atoms each of which is separated from the other by at least2 carbon atoms, alicyclic of from 6 to 12 carbon atoms, and aromaticlower alkyl; and the value of m and n is such that the diethyl formalmercaptan terminated polysulfide polymer and the mercaptan terminateddisulfide polymer have an average molecular weight of from 1,000 to4,000, such as 1,000 to 2,500. Such polymeric mixtures are described inU.S. Pat. No. 4,623,711 at col. 4, line 18 to col. 8, line 35, the citedportion of which being incorporated herein by reference. In some cases,R′ in the above formula is —CH₂—CH₂—; —C₂H₄—O—C₂H₄—; —C₂H₄—S—C₂H₄—;—C₂H₄—O—C₂H₄—O—C₂H₄—; or —CH₂—C₆H₄—CH₂—.

In certain embodiments, a polysulfide comprises a thiol-terminatedpolysulfide such as those commercially available from Akzo Nobel underthe name Thioplast® and from Toray under the name Thiokol®-LP.

A curing agent may be selected that is reactive with the terminal groupsof the sulfur-containing polymer and the sulfur-containing compound. Incertain embodiments, a sulfur-containing polymer and a sulfur-containingcompound provided by the present disclosure comprise the same groupsreactive with the curing agent. For example, in certain embodiments,both a sulfur-containing polymer and a sulfur-containing compoundprovided by the present disclosure comprise reactive thiol groups, andthe curing agent comprises reactive alkenyl groups, epoxy groups,isocyanate groups, or Michael acceptor groups.

In certain embodiments, a sulfur-containing compound provided by thepresent disclosure may be present in an amount from 0.1 wt % to 15 wt %of a composition, such as 0.1 to less than 5 wt %, 0.1 to less than 2 wt%, and in certain embodiments, 0.1 to less than 1 wt %, based on thetotal dry weight of the composition.

In certain embodiments, compounds provided by the present disclosurecomprise, in addition to the one or more sulfur-containing compoundsprovided by the present disclosure, one or more additional adhesionpromoters. A one or more additional adhesion promoter may be present inan amount from 0.1 wt % to 15 wt % of a composition, such as 0.1 to lessthan 5 wt %, 0.1 to less than 2 wt %, and in certain embodiments, 0.1 toless than 1 wt %, based on the total dry weight of the composition.Examples of adhesion promoters include phenolics, such as Methylon®phenolic resin, and organosilanes, such as epoxy, mercapto or aminofunctional silanes, such as Silquest® A-187 and Silquest® A-1100. Otheruseful adhesion promoters are known in the art.

In certain embodiments, a composition provided by the present disclosurecomprises an ethylenically unsaturated silane, such as, for example, asulfur-containing ethylenically unsaturated silane, which can improvethe adhesion of a cured sealant to a metal substrate. As used herein,the term sulfur-containing ethylenically unsaturated silane refers to amolecular compound that comprises, within the molecule, (i) at least onesulfur (S) atom, (ii) at least one, in some cases at least two,ethylenically unsaturated carbon-carbon bonds, such as a carbon-carbondouble bonds (C═C); and (iii) at least one silane group,—Si(—R)_(m)(—OR)_(3-m), where each R is independently selected fromhydrogen, alkyl, cycloalkyl, aryl, and others, and m is selected from 0,1, and 2. Examples of ethylenically unsaturated silanes are disclosed inU.S. Publication no. 2012/0040104, which is incorporated herein byreference.

In certain embodiments, a sulfur-containing ethylenically unsaturatedsilane, which is suitable for use in a composition provided by thepresent disclosure, comprises the reaction products of reactantscomprising (i) a mercaptosilane, and (ii) a polyene. As used herein, theterm mercaptosilane refers to a molecular compound that comprises,within the molecule, (i) at least one mercapto (—SH) group, and (ii) atleast one silane group. Suitable mercaptosilanes include, for example,those having a structure HS—R′—Si(—R)_(m)(—OR)_(3-m), where R and m aredefined as for a silane group, and R′ is a divalent organic group.

Examples of mercaptosilanes, which are suitable for use in preparing thesulfur-containing ethylenically unsaturated silanes includeγ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane,γ-mercaptopropylmethyldimethoxysilane,γ-mercaptopropylmethyldiethoxysilane, mercaptomethyltrimethoxysilanemercaptomethyltriethoxysilane, and combinations of any of the foregoing.

In certain embodiments, a polyene used to prepare sulfur-containingethylenically unsaturated silanes comprises a triene, which refers to acompound containing three carbon-carbon double bonds, such as, forexample, triallyl cyanurate and triallyl isocyanurate.

In certain embodiments, a polyene comprises a triene, such as one ormore of the foregoing triallyl compounds, and a mercaptosilane andtriene are reacted together in relative amounts such that the resultingreaction product theoretically comprises an average of at least twoethylenically unsaturated groups per molecule. In certain embodiments,an ethylenically unsaturated silane comprises the reaction products ofγ-mercaptopropyltrimethoxysilane and triallyl cyanurate.

In certain embodiments, compositions provided by the present disclosurecontain an essentially stoichiometric equivalent amount of thiol groupsto “ene” groups in order to obtain a cured sealant having acceptablesealant properties as described herein upon exposure of the compositionto actinic radiation. As used herein, “essentially stoichiometricequivalent” means that the number of thiol groups and “ene” groupspresent in the compositions differ by no more than 10% from each other,in some cases, no more than 5% or, in some cases, no more than 1% or nomore than 0.1%. In some cases, the number of thiol groups and “ene”groups present in the composition are equal. Moreover, as will beappreciated, the source of “ene” groups can include the ethylenicallyunsaturated silane itself (if used) as well as the other polyene(s)included in the composition. In certain embodiments, an ethylenicallyunsaturated silane is present in an amount such that 0.1 to 30, such as1 to 30, or, in some cases, 10 to 25 percent of the total number ofethylenically unsaturated groups present in the composition are part ofan ethylenically unsaturated silane molecule, based on the number ofethylenically unsaturated groups in the composition.

In certain embodiments, methods provided by the present disclosurecomprise exposing an uncured sealant composition to actinic radiation toprovide a cured sealant. In certain embodiments, particularly when thecured sealant is to be formed by exposure of the previously describeduncured sealant composition to UV radiation, the composition alsocomprises a photoinitiator. As will be appreciated by those skilled inthe art, a photoinitiator absorbs ultraviolet radiation and transformsit into a radical that initiates polymerization. Photoinitiators areclassified in two major groups based upon a mode of action, either orboth of which may be used in the compositions described herein.Cleavage-type photoinitiators include acetophenones,α-aminoalkylphenones, benzoin ethers, benzoyl oximes, acylphosphineoxides and bisacylphosphine oxides and mixtures thereof.Abstraction-type photoinitiators include benzophenone, Michler's ketone,thioxanthone, anthraquinone, camphorquinone, fluorone, ketocoumarin andmixtures thereof.

Non-limiting examples of suitable photoinitiators include benzil,benzoin, benzoin methyl ether, benzoin isobutyl ether benzophenol,acetophenone, benzophenone, 4,4′-dichlorobenzophenone,4,4′-bis(N,N′-dimethylamino)benzophenone, diethoxyacetophenone,fluorones, e.g., the H-Nu series of initiators available from SpectraGroup Ltd., 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthixantone, α-aminoalkylphenone, e.g.,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone,acylphosphine oxides, e.g., 2,6-dimethylbenzoyldlphenyl phosphine oxide,2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide,2,6-dichlorobenzoyldiphenylphosphine oxide, and2,6-dimethoxybenzoyldiphenylphosphine oxide, bisacylphosphine oxides,e.g., bis(2,6-dimethyoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide,bis(2,4,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, andbis(2,6-dichlorobenzoyl)-2,4,4-trimethylpentylphosphine oxide, andcombinations thereof.

In certain embodiments, a composition described herein comprise 0.01 upto 15 percent by weight of photoinitiator or, in some embodiments, 0.01up to 10 percent by weight, or, in yet other embodiments, 0.01 up to 5percent by weight of photoinitiator based on the total weight of thecomposition.

As described above, in certain embodiments, methods comprise exposing anuncured sealant composition to actinic radiation to provide a curedsealant. In certain embodiments, a thiol-ene reaction, which forms thecured sealant, can be carried out by irradiating an uncured compositioncomprising: (a) a thiol-terminated polythioether (such as any of thosedescribed above); (b) a sulfur-containing adhesion promoter, and (c) apolyene comprising a polyvinyl ether and/or a polyallyl compound asdescribed above, with actinic radiation. As used herein, actinicradiation encompasses electron beam (EB) radiation, ultraviolet (UV)radiation, and visible light. In many cases, a thiol-ene reaction iseffected by irradiating the composition with UV light and, in suchcases, as mentioned above; the composition often further comprises aphotoinitiator, among other optional ingredients.

Ultraviolet radiation from any suitable source which emits ultravioletlight having a wavelength ranging from, for example, 180 nm to 400 nm,may be employed to initiate the thiol-ene reaction described above andthereby form the cured sealant. Suitable sources of ultraviolet lightare generally known and include, for example, mercury arcs, carbon arcs,low pressure mercury lamps, medium pressure mercury lamps, high pressuremercury lamps, swirl-flow plasma arcs and ultraviolet light emittingdiodes. Certain embodiments of the compositions can exhibit an excellentdegree of cure in air at relatively low energy exposure in ultravioletlight.

In certain embodiments, compositions provided by the present disclosuremay be cured using actinic radiation. Examples of compositionscomprising polythioether compositions curable using actinic radiationare disclosed in U.S. Publication no. 2012/0040104. Such compositionsmay include, in addition to a sulfur-containing compound (adhesionpromoter) provided by the present disclosure, and one or moresulfur-containing polymers such as thiol-terminated sulfur-containingpolymers, a polyene such as a polyvinyl ether including, for example, apolyvinyl ether of Formula (14).

Although it is intended the compositions provided by the presentdisclosure are UV curable, as will be understood by those skilled in theart, other curing chemistries may also be employed with the use of oneor more appropriate curing agents. The term curing agent refers to acompound that can be added to a composition provided by the presentdisclosure to accelerate the curing or gelling of the composition.Curing or cure can refer to the point at which the sealant achieves acure hardness of 30 Durometer as measured according to ASTM D2240. Anysuitable curing agent can be used. In certain embodiments, a curingagent comprises an oxidizing agent that oxidizes terminal mercaptangroups to form disulfide bonds. Suitable oxidizing curing agentsinclude, for example, lead dioxide, manganese dioxide, calcium dioxide,sodium perborate monohydrate, calcium peroxide, zinc peroxide,dichromate and epoxy. Other suitable curing agents may contain reactivefunctional groups that are reactive with the functional groups in thesulfur-containing polymers disclosed herein. Examples include polythiolssuch as polythioethers; polyisocyanates such as isophorone,diisocyanate, and hexamethylene diisocyanate including mixtures thereofand including isocyanurate derivatives thereof; and polyepoxides.Examples of polyepoxides include hydantoin diepoxide, bisphenol-Aepoxides, bisphenol-F epoxides, Novolac type epoxides, aliphaticpolyepoxides, and any of the epoxidized unsaturated and phenolic resins.The term polyepoxide refers to a compound having a 1,2-epoxy equivalentgreater than one and includes monomers, oligomers, and polymers.

In certain embodiments, compositions provided by the present disclosurecomprise one or more curing agents such as an iso-epoxy, an isocyanate,and a combination thereof.

Compositions provided by the present disclosure may include one or morecatalysts.

Compositions provided by the present disclosure may comprise one or moredifferent types of filler. Suitable fillers include those commonly knownin the art, including inorganic fillers, such as carbon black andcalcium carbonate (CaCO₃), silica, polymer powders, and lightweightfillers. Suitable lightweight fillers include, for example, thosedescribed in U.S. Pat. No. 6,525,168. In certain embodiments, acomposition includes 5 wt % to 60 wt % of the filler or combination offillers, 10 wt % to 50 wt %, and in certain embodiments, from 20 wt % to40 wt %, based on the total dry weight of the composition. Compositionsprovided by the present disclosure may further include one or morecolorants, thixotropic agents, accelerators, fire retardants, adhesionpromoters, solvents, masking agents, or a combination of any of theforegoing. As can be appreciated, fillers and additives employed in acomposition may be selected so as to be compatible with each other aswell as the polymeric component, curing agent, and or catalyst.

In certain embodiments, compositions provided by the present disclosureinclude low density filler particles. As used herein, low density, whenused with reference to such particles means that the particles have aspecific gravity of no more than 0.7, in certain embodiments no morethan 0.25, and in certain embodiments, no more than 0.1. Suitablelightweight filler particles often fall within twocategories—microspheres and amorphous particles. The specific gravity ofmicrospheres may range from 0.1 to 0.7 and include, for example,polystyrene foam, microspheres of polyacrylates and polyolefins, andsilica microspheres having particle sizes ranging from 5 to 100 micronsand a specific gravity of 0.25 (Eccospheres®). Other examples includealumina/silica microspheres having particle sizes in the range of 5 to300 microns and a specific gravity of 0.7 (Fillite®), aluminum silicatemicrospheres having a specific gravity of from about 0.45 to about 0.7(Z-Light®), calcium carbonate-coated polyvinylidene copolymermicrospheres having a specific gravity of 0.13 (Dualite® 6001AE), andcalcium carbonate coated acrylonitrile copolymer microspheres such asDualite® E135, having an average particle size of about 40 μm and adensity of 0.135 g/cc (Henkel). Suitable fillers for decreasing thespecific gravity of the composition include, for example, hollowmicrospheres such as Expancel® microspheres (available from AkzoNobel)or Dualite® low density polymer microspheres (available from Henkel). Incertain embodiments, compositions provided by the present disclosureinclude lightweight filler particles comprising an exterior surfacecoated with a thin coating, such as those described in U.S. PublicationNo. 2010/0041839 at paragraphs [0016]-[0052], the cited portion of whichis incorporated herein by reference.

In certain embodiments, a low density filler comprises less than 2 wt %of a composition, less than 1.5 wt %, less than 1.0 wt %, less than 0.8wt %, less than 0.75 wt %, less than 0.7 wt % and in certainembodiments, less than 0.5 wt % of a composition, where wt % is based onthe total dry solids weight of the composition.

In certain embodiments, compositions provided by the present disclosurecomprise at least one filler that is effective in reducing the specificgravity of the composition. In certain embodiments, the specific gravityof a composition is from 0.8 to 1, 0.7 to 0.9, from 0.75 to 0.85, and incertain embodiments, is 0.8. In certain embodiments, the specificgravity of a composition is less than about 0.9, less than about 0.8,less than about 0.75, less than about 0.7, less than about 0.65, lessthan about 0.6, and in certain embodiments, less than about 0.55.

In certain embodiments, a thiol-terminated sulfur-containing polymerincluding a combination of thiol-terminated sulfur-containing polymerscomprises from about 50 wt % to about 90 wt % of a composition, fromabout 60 wt % to about 90 wt %, from about 70 wt % to about 90 wt %, andin certain embodiments, from about 80 wt % to about 90 wt % of thecomposition, where wt % is based on the total dry solids weight of thecomposition.

In certain embodiments, a thiol-terminated polythioether including acombination of thiol-terminated polythioethers comprises from about 50wt % to about 90 wt % of a composition, from about 60 wt % to about 90wt %, from about 70 wt % to about 90 wt %, and in certain embodiments,from about 80 wt % to about 90 wt % of the composition, where wt % isbased on the total dry solids weight of the composition.

A composition may also include any number of additives as desired.Examples of suitable additives include plasticizers, pigments,surfactants, adhesion promoters, thixotropic agents, fire retardants,masking agents, and accelerators (such as amines, including1,4-diaza-bicyclo[2.2.2]octane, DABCO®), and combinations of any of theforegoing. When used, the additives may be present in a composition inan amount ranging, for example, from about 0% to 60% by weight. Incertain embodiments, additives may be present in a composition in anamount ranging from about 25% to 60% by weight.

Uses

Compositions provided by the present disclosure may be used, forexample, in sealants, coatings, encapsulants, and potting compositions.A sealant includes a composition capable of producing a film that hasthe ability to resist operational conditions, such as moisture andtemperature, and at least partially block the transmission of materials,such as water, fuel, and other liquid and gases. A coating compositionincludes a covering that is applied to the surface of a substrate to,for example, improve the properties of the substrate such as theappearance, adhesion, wettability, corrosion resistance, wearresistance, fuel resistance, and/or abrasion resistance. A pottingcomposition includes a material useful in an electronic assembly toprovide resistance to shock and vibration and to exclude moisture andcorrosive agents. In certain embodiments, sealant compositions providedby the present disclosure are useful, e.g., as aerospace sealants and aslinings for fuel tanks.

In certain embodiments, compositions, such as sealants, may be providedas multi-pack compositions, such as two-pack compositions, wherein onepackage comprises one or more thiol-terminated polythioethers providedby the present disclosure and a second package comprises one or morepolyfunctional sulfur-containing epoxies provided by the presentdisclosure. Additives and/or other materials may be added to eitherpackage as desired or necessary. The two packages may be combined andmixed prior to use. In certain embodiments, the pot life of the one ormore mixed thiol-terminated polythioethers and epoxies is at least 30minutes, at least 1 hour, at least 2 hours, and in certain embodiments,more than 2 hours, where pot life refers to the period of time the mixedcomposition remains suitable for use as a sealant after mixing.

Compositions, including sealants, provided by the present disclosure maybe applied to any of a variety of substrates. Examples of substrates towhich a composition may be applied include metals such as titanium,stainless steel, and aluminum, any of which may be anodized, primed,organic-coated or chromate-coated; epoxy; urethane; graphite; fiberglasscomposite; Kevlar®; acrylics; and polycarbonates. In certainembodiments, compositions provided by the present disclosure may beapplied to a coating on a substrate, such as a polyurethane coating.

Compositions provided by the present disclosure may be applied directlyonto the surface of a substrate or over an underlayer by any suitablecoating process known to those of ordinary skill in the art.

The time to form a viable seal using curable compositions of the presentdisclosure can depend on several factors as can be appreciated by thoseskilled in the art, and as defined by the requirements of applicablestandards and specifications. In general, curable compositions of thepresent disclosure develop adhesion strength within 24 hours to 30hours, and 90% of full adhesion strength develops from 2 days to 3 days,following mixing and application to a surface. In general, full adhesionstrength as well as other properties of cured compositions of thepresent disclosure becomes fully developed within 7 days followingmixing and application of a curable composition to a surface.

Cured compositions such as cured sealants exhibit properties acceptablefor use in aerospace applications. In general, it is desirable thatsealants used in aviation and aerospace applications exhibit thefollowing properties: peel strength greater than 20 pounds per linearinch (pli) on Aerospace Material Specification (AMS) 3265B substratesdetermined under dry conditions, following immersion in JRF for 7 days,and following immersion in a solution of 3% NaCl according to AMS 3265Btest specifications; tensile strength between 300 pounds per square inch(psi) and 400 psi; tear strength greater than 50 pounds per linear inch(pli); elongation between 250% and 300%; and hardness greater than 40Durometer A. These and other cured sealant properties appropriate foraviation and aerospace applications are disclosed in AMS 3265B, theentirety of which is incorporated herein by reference. It is alsodesirable that when cured, curable compositions of the presentdisclosure used in aviation and aircraft applications exhibit a percentvolume swell not greater than 25% following immersion for one week at60° C. (140° F.) and ambient pressure in JRF type 1. Other properties,ranges, and/or thresholds may be appropriate for other sealantapplications.

In certain embodiments, compositions provided by the present disclosureare fuel-resistant. As used herein, the term “fuel resistant” means thata composition, when applied to a substrate and cured, can provide acured product, such as a sealant, that exhibits a percent volume swellof not greater than 40%, in some cases not greater than 25%, in somecases not greater than 20%, in yet other cases not more than 10%, afterimmersion for one week at 140° F. (60° C.) and ambient pressure in JetReference Fluid (JRF) Type I according to methods similar to thosedescribed in ASTM D792 (American Society for Testing and Materials) orAMS 3269 (Aerospace Material Specification). Jet Reference Fluid JRFType I, as employed for determination of fuel resistance, has thefollowing composition: toluene: 28±1% by volume; cyclohexane(technical): 34±1% by volume; isooctane: 38±1% by volume; and tertiarydibutyl disulfide: 1±0.005% by volume (see AMS 2629, issued Jul. 1,1989, §3.1.1 etc., available from SAE (Society of AutomotiveEngineers)).

In certain embodiments, compositions provide a cured product, such as asealant, exhibiting an elongation of at least 100% and a tensilestrength of at least 400 psi when measured in accordance with theprocedure described in AMS 3279, §3.3.17.1, test procedure AS5127/1,§7.7.

In certain embodiments, compositions provide a cured product, such as asealant, that exhibits a lap shear strength of greater than 200 psi andin some cases at least 400 psi when measured according to the proceduredescribed in SAE AS5127/1 paragraph 7.8.

In certain embodiments, compositions provided by the present disclosureprovide a cured sealant having a lap shear strength of >200 psi, such asat least 220 psi, or, in certain embodiments, at least 250 psi, whenmeasured according to Paragraph 7.8 of AS 5127/1.

In certain embodiments, a cured sealant comprising a compositionprovided by the present disclosure meets or exceeds the requirements foraerospace sealants as set forth in AMS 3277.

Curable compositions of the present disclosure can exhibit a T_(g) whencured of −55° C. or less, in certain embodiments, −60° C. or less, andin certain embodiments −65° C. or less. The glass transitiontemperature, T_(g), can be measured by differential scanningcalorimetry.

Furthermore, methods are provided for sealing an aperture utilizing acomposition provided by the present disclosure. These methods comprise,for example, applying a composition provided by the present disclosuresuch as a sealant to a surface to seal an aperture, and curing thecomposition. In certain embodiments, a method for sealing an aperturecomprises (a) applying a sealant composition provided by the presentdisclosure to one or more surfaces defining an aperture, (b) assemblingthe surfaces defining the aperture, and (c) curing the sealant, toprovide a sealed aperture.

In certain embodiments, a composition may be cured under ambientconditions, where ambient conditions refer to a temperature from 20° C.to 25° C. In certain embodiments, a composition may be cured underconditions encompassing a temperature from a 0° C. to 100° C. In certainembodiments, a composition may be cured at a higher temperature such asat least 30° C., at least 40° C., and in certain embodiments, at least50° C. In certain embodiments, a composition may be cured at roomtemperature, e.g., 25° C. In certain embodiments, a composition may becured upon exposure to actinic radiation such as ultraviolet radiation.As will also be appreciated, the methods may be used to seal apertureson aerospace vehicles including aircraft and aerospace vehicles.

Apertures, including apertures of aerospace vehicles, sealed withcompositions provided by the present disclosure are also disclosed.

EXAMPLES

Embodiments provided by the present disclosure are further illustratedby reference to the following examples, which describe the synthesis,properties, and uses of certain sulfur-compounds and compositionscomprising such sulfur-containing compounds. It will be apparent tothose skilled in the art that many modifications, both to materials, andmethods, may be practiced without departing from the scope of thedisclosure.

Example 1

In a 300 mL, 3-necked, round-bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 98 g (0.394 mol) oftriallylcyanurate (TAC) and 215 g of 1,8-dimercapto-3,6-dioxaoctane(DMDO) were charged, and the mixture stirred at room temperature for 20minutes. The mixture was then heated to 70° C., and 100 mg ofVazo®-67(Dupont) was added. The reaction mixture was maintained at 70°C. for 8 hours to provide thiol-terminated intermediate A. The progressof the reaction was monitored by determining the mercaptan equivalentweight (MEW). The final MEW was 297, and the material had a viscosity of20 poise at 25° C., spindle #6 at 50 RPM, measured using a CAP2000viscometer.

In a 300 mL, 3-necked, round bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 99 g (0.374 mol) ofthiol-terminated intermediate A was added. Then, 18 g (0.123 mol) ofvinyltrimethoxysilane (Silquest® A-171, Momentive Performance Materials)was slowly added to the flask. The reaction was stirred until thetemperature stabilized. After the temperature stabilized, thetemperature of the reaction was set to 70° C. and 100 mg of Vazo®-67 wasadded. The progress of the reaction was monitored by MEW. The reactionwas complete in 12 hours to provide sulfur-containing compound 1 with afinal MEW of 431.

Example 2

In a 300 mL, 3-necked, round-bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 58 g (0.218 mol) ofthiol-terminated intermediate A of Example 1 and 7.8 g of vinylphosphonic acid (VPA) were added at 18° C. After addition, there was asmall exotherm to 21° C. The temperature of the reaction was set to 65°C. and 75 mg of Vazo®-67 was added. The reaction was stirred for 6hours. The reaction was restarted again after sitting for 17 hours atroom temperature and 70 mg of Vazo®-67 was added. After stirring for anadditional 4 hours at elevated temperature, the reaction was complete.The final MEW of sulfur-containing compound 2 was 436.

Example 3

In a 300 mL, 3-necked, round-bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 36 g (0.127 mol) ofthiol-terminated intermediate A of Example 1 and 5.7 g of vinylphosphonic methyl ester (VPA) were added at 18° C. After addition therewas a small exotherm to 21° C. The temperature of the reaction was setto 100° C. and 171 mg of Vazo®-67 was added. The reaction was stirredfor 14 hours. The final MEW of sulfur-containing compound 3 was 456.

Example 4

In a 300 mL, 3-necked, round-bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 49 g (0.476 mol)diethylenetriamine, 54 g (0.475 mol) allylglycidol ether, and 43 g(0.714 mol) isopropyl alcohol (IPA) were added at room temperature andstirred for 10 minutes. The temperature was then set to 64° C. and after10 minutes increased to 120° C. The reaction was removed from the heatsource, while stirring. The reaction was monitored by determining theepoxide equivalent weight (EEW). When the EEW reached 5412, 94% of theepoxide was consumed and the reaction was stopped to provide1-(allyloxy)-3-(2-(2-aminoethylamino)ethylamino)propan-2-ol. The IPA wasremoved by rotary evaporation.

In a 300 mL, 3-necked, round-bottom flask fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 5 g (0.026 mol) of1-(allyloxy)-3-(2-(2-aminoethylamino)ethylamino)propan-2-ol and 22.48 g(0.026 mol) of thiol-terminated intermediate A of Example 1, and 100 mgof Vazo®-67 were added. The temperature of the reaction was set to 80°C. and the reaction was monitored by MEW. After 2 hours, the reactionwas complete and the final MEW of sulfur-containing compound 4 was 549.

Example 5

In a 300 mL, 3-necked, round bottom flask, fitted with a thermal probe,mechanical stirrer, and nitrogen (N₂) inlet, 6.3 g (0.062 mol) ofaminopropylvinylether and 53.5 g (0.069 mol) of the thiol-terminatedintermediate A of Example 1 were added. The temperature of the reactionwas set to 80° C. and 50 mg of Vazo®-67 was added. The reaction wasmonitored by MEW. After two hours the MEW of the reaction was 445,indicating that about one-third of the mercaptan groups were reacted andthe reaction was considered complete. The viscosity was 350 poise withspindle #6, 50 RPM, measured using a CAP2000 viscometer.

Example 6 Comparative Composition 1

The components of Comparative Composition 1 are shown in Table 1.

TABLE 1 Comparative Composition 1. Component Charge (g) Weight (%)**Polythioethers^(§) 40 92.7 TEG-DVE 2.3 5.3 TAC-sil 0.34 0.78 Silane*0.34 0.79 Irgacure ® 2022 0.21 0.49 *Silane is3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane. **Weight %based on total solids weight of the composition. ^(§)Thiol-terminatedpolythioethers of the type described in U.S. Pat. No. 6,172,179, averagethiol functionality: 2.05-2.95, commercially available from PRC-DesotoInternational, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, triethyeneglycol divinyl ether(TEG-DVE), the adduct described in Example 12 of U.S. Publication No.2012/0040104 (TAC-Sil), and 3-(N-styrylmethyl-2-aminoethylamino)propyltrimethoxysilane (Gelest, Morrisville, Pa.) were added to the60-gram container. The container was place in a high-speed mixer (DAC600 FVZ) and mixed for 30 seconds at 2,300 rpm. The container wasopened, Irgacure® 2022(BASF) was added, and the container placed in thespeed mixer and the composition mixed for 1 minute at 2,300 rpm.

Example 7 Composition 2

The components of Composition 2 are shown in Table 2.

TABLE 2 Composition 2. Component Charge (g) Weight (%)**Polythioethers^(§) 40 90.3 Compound 1, Example 1 1.07 2.42 TEG-DVE 2.345.3 TAC-sil 0.334 0.75 Silane* 0.338 0.76 Irgacure ® 2022 0.22 0.50*Silane is 3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane.**Weight % based on total solids weight of the composition.^(§)Thiol-terminated polythioethers of the type described in U.S. Pat.No. 6,172,179, average thiol functionality: 2.05-2.95, commerciallyavailable from PRC-Desoto International, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, sulfur-containing adhesion promoter 1of Example 1, triethyene glycol divinyl ether (TEG-DVE), the adductdescribed in Example 12 of U.S. Publication No. 2012/0040104 (TAC-Sil),and 3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane (Gelest,Morrisville, Pa.) were added to the 60-gram container. The container wasplaced in a high-speed mixer (DAC 600 FVZ) and mixed for 30 seconds at2,300 rpm. The container was opened, Irgacure® 2022 (BASF) added, andthe composition mixed for 1 minute at 2,300 rpm.

Example 8 Composition 3

The components of Composition 3 are shown in Table 3.

TABLE 3 Composition 3. Component Charge (g) Weight (%)**Polythioethers^(§) 50 90.1 Compound 2, Example 2 1.4 2.5 TEG-DVE 3.2 5.8TAC-sil 0.61 1.1 Iracure ® 2022 0.275 0.50 *Silane is3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane. **Weight %based on total solids weight of the composition. ^(§)Thiol-terminatedpolythioethers of the type described in U.S. Pat. No. 6,172,179, averagethiol functionality: 2.05-2.95, commercially available from PRC-DesotoInternational, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, the sulfur-containing adhesion promoter2 of Example 2, triethyene glycol divinyl ether (TEG-DVE), and theadduct described in Example 12 of U.S. Publication No. 2012/0040104(TAC-Sil), were added to the 60-gram container. The container was placedin a high-speed mixer (DAC 600 FVZ) and mixed for 30 seconds for 2,300rpm. The container was opened, Irgacure® 2022 (BASF) added, and thecomposition mixed for 1 minute at 2,300 rpm.

Example 9 Composition 4

The components of Composition 4 are shown in Table 4.

TABLE 4 Composition 4. Component Charge (g) Weight (%)**Polythioethers^(§) 50 83.9 Compound 3, Example 3 1.44 2.4 TEGDVE 2.233.7 TAC 0.79 1.3 TAC-sil 0.7 1.2 Silane* 1.1 1.8 Silquest ® A-1120 0.280.47 Silica 2.8 4.70 Irgacure ® 2022 0.28 0.47 *Silane is3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane^(§)Thiol-terminated polythioethers of the type described in U.S. Pat.No. 6,172,179, average thiol functionality: 2.05-2.95, commerciallyavailable from PRC-Desoto International, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, the sulfur-containing adhesion promoter3 of Example 3, triethyene glycol divinyl ether (TEG-DVE), the adductdescribed in Example 12 of U.S. Publication No. 2012/0040104 (TAC-Sil),3-(N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane (Gelest,Morrisville, Pa.), Silquest A-1120, and silica were added to the 60-gramcontainer. The container was place in a high-speed mixer (DAC 600 FVZ)and mixed for 30 seconds at 2,300 rpm. The container was opened,Irgacure® 2022 (BASF) added, and the composition mixed for 1 minute at2,300 rpm.

Example 10 Composition 5

The components of Composition 5 are shown in Table 5.

TABLE 5 Composition 5. Component Charge (g) Weight (%)**Polythioethers^(§) 50 91.1 Compound 4, Example 4 1.5 2.7 TEG-DVE 2.7 4.9TAC-sil 0.67 1.2 Irgacure ® 2022 0.27 0.49 ^(§)Thiol-terminatedpolythioethers of the type described in U.S. Pat. No. 6,172,179, averagethiol functionality: 2.05-2.95, commercially available from PRC-DesotoInternational, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, the sulfur-containing adhesion promoter4 of Example 4, triethyene glycol divinyl ether (TEG-DVE), and theadduct described in Example 12 of U.S. Publication No. 2012/0040104(TAC-Sil) were added to the 60-gram container. The container was placein a high-speed mixer (DAC 600 FVZ) and mixed for 30 seconds for 2,300rpm. The container was opened, Irgacure® 2022 (BASF) was added, and thecomposition mixed for 1 minute at 2,300 rpm.

Example 11 Composition 6

The components of Composition 6 are shown in Table 6.

TABLE 6 Composition 6. Component Charge (g) Weight (%)**Polythioethers^(§) 50 91.1 Compound 5, Example 5 1.2 2.2 TEG-DVE 2.7 4.9TAC-sil 0.67 1.2 Irgacure ® 2022 0.27 0.49 ^(§)Thiol-terminatedpolythioethers of the type described in U.S. Pat. No. 6,172,179, averagethiol functionality: 2.05-2.95, commercially available from PRC-DesotoInternational, Inc., Sylmar, CA.

Mixing was performed in a 60-gram plastic container with a lid. Thethiol-terminated polythioethers, the sulfur-containing adhesion promoterof Example 5, triethyene glycol divinyl ether (TEG-DVE), and the adductdescribed in Example 12 of U.S. Publication No. 2012/0040104 (TAC-Sil)were added to the 60-gram container. The container was place in ahigh-speed mixer (DAC 600 FVZ) and mixed for 30 seconds for 2,300 rpm.The container was opened, Irgacure® 2022 (BASF) was added, and thecomposition mixed for 1 minute at 2,300 rpm.

Example 12 Adhesion Measurement

The mixed compositions of Examples 6-8, 10, and 11 were individuallypoured onto an anodized aluminum panel (Mil-227725), and placed under UVlight for 90 seconds, after which time the compositions had cured to atack-free solid. The compositions were cured using a Phoseon Fireflycuring unit, available from Phoseon Technology, Hillsboro, Oreg.

The cured panels were maintained at ambient conditions for apredetermined number of days, after which time, adhesion was measured aspercent of cohesive failure. An adhesion scale ranging from 0 to 5 wasassigned to each test, with a value of 5 being 100% cohesive failure anda value of 0 being 100% adhesive failure. (Note that the adhesion testmethod is not a standardized test).

The adhesion of the cured compositions are shown in Table 7.

TABLE 7 Adhesion of compositions to anodized aluminum panels. AdhesionComposition Promoter Anodized Comparative Composition 1, none 3 Example6 Composition 2, Example 7 1 5 Composition 3, Example 8 2 4 Composition5, Example 10 4 5 Composition 6, Example 11 5 5

The results demonstrate that compositions comprising copolymerizablesulfur-containing adhesion promoters provided by the present disclosureexhibit enhanced adhesion to anodized aluminum substrates compared tosimilar compositions without a copolymerizable sulfur-containingadhesion promoter.

Finally, it should be noted that there are alternative ways ofimplementing the embodiments disclosed herein. Accordingly, the presentembodiments are to be considered as illustrative and not restrictive.Furthermore, the claims are not to be limited to the details givenherein, and are entitled their full scope and equivalents thereof.

What is claimed is:
 1. A sulfur-containing compound comprising thereaction product of: a thiol-terminated intermediate comprising thereaction product of triallylcyanurate and1,8-dimercapto-3,6-dioxaoctane; and a compound having a terminal alkenylgroup that promotes adhesion.
 2. The sulfur-containing compound of claim1, wherein the sulfur-containing compound comprises an average of aboutone group that promotes adhesion per molecule or an average of about twogroups that promote adhesion per molecule.
 3. The sulfur-containingcompound of claim 1, wherein the group that promotes adhesion isselected from a silane, a phosphonate, an amine, a carboxylic acid, anda phosphonic acid.
 4. The sulfur-containing compound of claim 1, whereinthe compound having a terminal alkenyl group and a group that promotesadhesion comprises a compound having the structure of Formula (2):CH₂═CH₂—R⁴—Si(R⁵)_(y1)(OR⁶)_(y2)  (2) wherein y1 is selected from 0, 1,and 2; y2 is selected from 1, 2, and 3; and the sum of y1 and y2 is 3;R⁴ is selected from a covalent bond and C₁₋₆ alkanediyl; each R⁵ isindependently selected from C₁₋₄ alkyl; and each R⁶ is independentlyselected from C₁₋₄ alkyl.
 5. The sulfur-containing compound of claim 1,wherein the compound having a terminal alkenyl group and a group thatpromotes adhesion comprises a compound selected fromtrimethoxy(vinyl)silane, ethoxydimethoxy(vinyl)silane,diethoxy(methoxy)(vinyl)silane, triethoxy(vinyl)silane, and acombination of any of the foregoing.
 6. The sulfur-containing compoundof claim 1, wherein the compound having a terminal alkenyl group and agroup that promotes adhesion comprises a compound having the structureof Formula (3):CH₂═CH₂—R⁷—P(═O)(OR⁸)₂  (3) wherein R⁷ is selected from a covalent bondand C₁₋₆ alkanediyl; and each R⁸ is independently selected from hydrogenand C₁₋₄ alkyl.
 7. The sulfur-containing compound of claim 1, whereinthe compound having a terminal alkenyl group and a group that promotesadhesion comprises a compound selected from vinylphosphonic acid,dimethyl vinylphosphonate, ethyl methyl vinylphosphonate, diethylvinylphosphonate, vinyl phosphonic methyl ester, and a combination ofany of the foregoing.
 8. The sulfur-containing compound of claim 1,wherein the having a terminal alkenyl group and a group that promotesadhesion comprises a compound having the structure of Formula (4):CH₂═CH₂—R⁹—NH₂  (4) wherein R⁹ is selected from C₁₋₁₀ alkanediyl,substituted C₁₋₁₀ alkanediyl, C₁₋₁₀ heteroalkanediyl, and substitutedC₁₋₁₀ heteroalkanediyl.
 9. The sulfur-containing compound of claim 1,wherein the compound having a terminal alkenyl group and a group thatpromotes adhesion comprises a compound selected from1-(allyloxy)-3-(2-(2-aminoethylamino)ethylamino)propan-2-ol,aminopropylvinylether, and a combination thereof.
 10. Thesulfur-containing compound of claim 1, wherein the compound having aterminal alkenyl group and a group that promotes adhesion comprises acompound having the structure of Formula (5):CH₂═CH₂—R¹⁰—COOH  (5) wherein R¹⁰ is C₁₋₆ alkanediyl.
 11. A compositioncomprising: at least one sulfur-containing compound of claim 1; at leastone thiol-terminated sulfur-containing polymer; and at least one curingagent.
 12. The composition of claim 11, wherein the at least onethiol-terminated sulfur-containing polymer is selected from athiol-terminated polythioether and a thiol-terminated polysulfide. 13.The composition of claim 11, wherein the at least one thiol-terminatedsulfur-containing polymer is selected from a thiol-terminatedpolythioether of Formula (13), a thiol-terminated polythioether ofFormula (13a), and a combination thereof:(a) HS—R¹—[—S—(CH₂)_(p)—O—(R²—O)_(m)—(CH₂)₂—S—R¹—]_(n)—SH  (13)(b)(c) {HS—R¹—[—S—(CH₂)_(p)—O—(R²—O)_(m)—(CH₂)₂—S—R¹—]S—V′—}_(z)B  (13a)wherein: (d) each R¹ independently is selected from C₂₋₁₀ alkanediyl,C₆₋₈ cycloalkanediyl, C₆₋₁₀ alkanecycloalkanediyl, C₅₋₈heterocycloalkanediyl, and —[(—CHR³—)_(s)—X—]_(q)—(—CHR³—)_(r)—,wherein: (e) s is an integer from 2 to 6; (f) q is an integer from 1 to5; (g) r is an integer from 2 to 10; (h) each R³ is independentlyselected from hydrogen and methyl; and (i) each X is independentlyselected from O, S, and —NHR—, wherein R is selected from hydrogen andmethyl; each R² is independently selected from C₁₋₁₀ alkanediyl, C₆₋₈cycloalkanediyl, C₆₋₁₄ alkanecycloalkanediyl, and—[(—CHR³—)_(s)—X—]_(q)—(—CHR³—)_(r)—, wherein s, q, r, R³, and X are asdefined above; (j) m is an integer from 0 to 50; (k) n is an integerfrom 1 to 60; (l) p is an integer from 2 to 6; (m) B represents a coreof a z-valent, vinyl-terminated polyfunctionalizing agent B(—V)_(z)wherein: (n) z is an integer from 3 to 6; and (o) —V is a moietycomprising a group that is reactive with a thiol group; and (p) each—V′— represents a moiety formed by the reaction of —V with a thiolgroup.
 14. The composition of claim 11, wherein the at least one curingagent is selected from an iso-epoxy and an isocyanate.
 15. Thecomposition of claim 11, comprising at least one second adhesionpromoter.
 16. The composition of claim 11, formulated as a sealant. 17.A cured sealant comprising the composition of claim
 16. 18. The curedsealant of claim 16, exhibiting 100% cohesive failure.
 19. An aperturesealed with a sealant comprising the composition of claim
 16. 20. Amethod of sealing an aperture comprising: (a) applying a sealantcomprising the composition of claim 16 to an aperture; and (b) curingthe applied sealant to provide a sealed aperture.